The Fit Brain

You love the runner’s high, chiseled physique, steady energy, knock-out sleep, and that alluring post-workout glow. And, sure, there’s always the extraordinary cardiovascular benefit, cancer deterrent, anti-inflammatory impact, and age reversal effect. If that isn’t enough congratulations for your fitness endeavors, here’s more. Physical activity helps fortify your brain as well as your muscles. Yes, exercise goes to your head in dramatically healthy ways – throughout the course of a lifetime. Let’s examine.

Changing the Brain

Exercise supports the brain in a number of ways. Most obviously, exercise increases blood flow to the brain, which provides more oxygen and energy but also reduces free radical damage and enhances memory. Researchers also know that exercise stimulates the creation of new neurons and the production of brain-derived neurotrophic factor (BDNF), a chemical that is instrumental in neuron preservation and formation. And then there’s the impact on gene expression (always a favorite of mine). Exercise specifically promotes gene expression that supports plasticity, the brain’s crucial power to alter neural pathways.

A more recent study highlights exercise’s role in boosting the brain’s stem cell activity – essentially the ability to divide and differentiate throughout our lifetime. Research at Northwestern University’s Feinberg School of Medicine shows that exercise moderates the activity of bone-morphogenetic protein (BMP), which reduces stem cell responsiveness in the brain. Within a weeks’ time, BMP levels were halved in lab mice that ran on a wheel, and an opposing protein called Noggin increased. As a result, the mice displayed remarkable adeptness in cognitive tests.

In addition to enhancing cognitive performance and stimulating ongoing brain growth, exercise also influences the chemical balance related to mood. Research has long connected physical activity with relief of depression and anxiety. Exercise not only stimulates the brain’s release of “feel good chemicals” like endorphins that induce calm and contentment but also supports the brain’s efficient use of dopamine by increasing the number of receptors and the time dopamine remains in the synapses (PDF).

When it comes to the “aging brain,” exercise rewrites the script on that notion. Physical activity can not only preserve brain function but can turn back the clock. As mentioned, exercise keeps the brain’s stem cells working efficiently over the course of a lifetime and preserve brain tissue density. The difference shows. When researchers scanned the brains of fifty-five subjects (ages 55-79), those with the fittest profile (as measured by their maximal oxygen uptake) showed significant differences in the frontal, temporal, and parietal regions of the brain, areas related to learning and memory functions.

Researchers have also found that sustained exercise improves cognitive measures in older adults already experiencing mild memory loss.

Which Exercise?

So, what kind of exercise and how much are we talking here? Science is currently chasing that one down. A Taiwanese study compared mice that played on wheel at their own pace versus mice that were provoked to run at fast speeds. Although researchers found changes in the brains of both groups, the mice that got the more intense workout sported more numerous and more cognitively complex alterations. Their conclusion? Different exercise elicits different changes. Other research, however, suggests that more intense cardiovascular activity spurs more dramatic improvements in cognition and memory. And let’s not leave out resistance training. A recent Canadian study found that resistance training improved executive functioning measures related to attention and conflict resolution. Moderate levels of exercise appear to be effective, but any level – and amount – of activity leaves a positive impact.


The evidence clearly shows, however, that exercise sharpens our mental acuity at any point in our lives. In children, of course, there are plenty of cognitive and behavioral benefits. Study after study (PDF) has demonstrated that physical activity boosts academic performance as well as cognitive related functioning itself in areas such as attention, planning, and organization. (Was there ever any question on that one?)

Most research, however, has focused on older adults who have either been active throughout their lives and those who take up exercise in their later years. The fact is, the more sustained exercise is over a lifetime, the better. Research suggests that a “cognitive reserve” exists in those who were active early in life. Every workout adds to the overall – and lasting – benefit. Finally, experts believe that the best impact comes from a potent synergy between exercise and good nutrition. Now where have I heard that one before?

Have a great day, everyone, and be sure to share your thoughts!

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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